הרב יעקב עמדן

Rav Yaakov Yisrael ben Tzvi (15 Sivan 5458/1698–30 Nisan 5536/1776), the Yaavetz, was among the great chachmei Ashkenaz of the eighteenth century and a determined defender of tradition. His acronym Yaavetz stands for Yaakov ben Tzvi: he was the son of the Chacham Tzvi, Rav Tzvi Ashkenazi, under whom he learned in Altona and Amsterdam until the age of seventeen. He married Rachel, daughter of Rav Mordechai HaKohen Katz of Ungarisch-Brod, and after mastering the whole of Talmud broadened his learning to grammar, Kabbalah, and philosophy.

He generally refused to hold rabbinic office. For a few years he served the rabbanut of Emden — from which he took his name — but he soon returned to his native Altona, where he received permission from the Danish king to open a Hebrew printing press, supported himself through commerce, and declined the rabbanut for the rest of his life. He wrote more than sixty works. Best known is his Siddur Yaavetz (Amudei Shamayim, also called Beis Yaakov), a commentary on the tefillos of the whole year together with their dinim and minhagim; beside it stand his responsa Sheilas Yaavetz, Mor uKetziah on the Tur and Shulchan Aruch, Lechem Shamayim on the Mishnah, Mitpachas Sefarim, and his autobiography Megillas Sefer.

The Yaavetz was a leading opponent of the Sabbatean movement that still lingered in his day. In its course he came to accuse Rav Yonatan Eybeschutz of covert Sabbateanism, reading such allusions into amulets that Rav Eybeschutz had written; the dispute grew bitter, drew in rabbanim across Germany, Poland, France, and Holland, reached the secular courts, and for a time forced the Yaavetz to leave Altona for Amsterdam before he was permitted to return. Its echoes continued long after both men were gone; the accepted view within the Orthodox world is that Rav Eybeschutz was not a Sabbatean. Alongside this controversy the Yaavetz devoted himself to guarding the received tradition, and he was among the first to question, on internal grounds, the ascription of parts of the Zohar to Rav Shimon bar Yochai.

He was niftar in Altona on 30 Nisan 5536 (1776), as he was preparing to go up to Eretz Yisrael. His glosses on the Talmud are printed at the back of the Vilna Shas, and his siddur is used to this day.